1. Field of the Invention
The present invention relates to relayless and fuseless junction boxes and power distribution units.
2. Background Art
Junctions boxes and power distribution units are units commonly used to distribute or relay power and other electrical signals to one or more subsystem. The units typically include one or more mechanical relays and one or more fuses. The relays are typically used to open and close high current electrical connections and the fuses are typically used to generate open circuits during fault conditions, such as to provide protection to a load.
Fuses tend to be one-use items which must be replaced if opened during fault conditions, i.e., if the fuse blows. The replacement or rework of blown fuses can be problematic and expensive. Fuses may fail to provide feedback or other empirical indicators which may be useful in diagnosing the fault conditions that cause the fuse to blow. Fuses also fail to provide early warning indicators prior to the occurrence of such fault conditions.
Relays tend to be relatively expensive items which require removal or rework should they fail or otherwise require repair. Their mechanical nature tends to limit control functionality and often results in instable load current characteristics, such as in-rush, ripple, noise, etc.). The opening of relays may also be problematic in that the relays tend to bounce rather than immediately shutting off the current supply, causing spikes and other trickle currents to keep flowing to the subsystem associated therewith.
Relays and fuses tend to be fairly large in size and consume corresponding large portions of printed circuit boards (PCBs). This can lead to design constraints and other problems associated with packaging the PCBs in vehicles and other environments. Relays and fuses tend to have short lead time to fail, forcing OEMs to make the PCB, fuses, and relays serviceable and accessible by the user.